


"Don't Forget"

by Its_Raining_Here



Category: Undertale (Video Game)
Genre: Angst, Depressed Sans (Undertale), Diary/Journal, Implied/Referenced Character Death, Implied/Referenced Self-Harm, Invasion of Privacy, Kinda, M/M, Post-Accident W. D. Gaster, Scientist Sans (Undertale), Scientist W. D. Gaster, Soul Bond, Soulmates, headcanons about monster marriage, just with the blood on the pages, papyrus we call it a secret for a reason
Language: English
Status: Completed
Published: 2020-12-19
Updated: 2020-12-19
Packaged: 2021-03-11 01:48:43
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,979
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28167276
Author URL: https://archiveofourown.org/users/Its_Raining_Here/pseuds/Its_Raining_Here
Summary: Sans hides so much from Papyrus, so when the taller skeleton is presented with answers to his questions, he welcomes them with open arms.Or an open book.
Relationships: W. D. Gaster/Sans
Comments: 11
Kudos: 87





	"Don't Forget"

**Author's Note:**

> i was sad while writing this so now you're gonna be sad too.

Papyrus hadn’t meant to snoop.

Really, he only wanted to clean up Sans’ room a bit! It wasn’t his fault that he found the book secretly hidden underneath the mattress…okay now he sees where he may have overstepped.

But of all the things he was expecting to find underneath his brother's bed, a journal was not one of them. 

He didn’t think Sans was the type to keep a journal. 

Then again, he didn’t think Sans was the type to try and make a self sustaining tornado, yet he did that just fine.

Of course, when one is presented with a book that was obviously meant to be a secret, a normal person would simply put the book back where they found it.

Papyrus wasn’t a normal person though.

He questioned if he should really be reading this, seeing as it felt like an invasion of his brother's privacy.

Well, that’s because it was.

Papyrus had no business reading though Sans’ journal. But what could Sans possibly be hiding? He knew the smaller skeleton kept more secrets than most monsters. Maybe Papyrus could help Sans with whatever he was hiding!

That seemed reason enough for him, because the next thing he knew, Papyrus was opening the book.

.  
.  
.

He wasn’t even past the first page, and he was already concerned.

_dear future sans,  
please for the love of god don’t ever read this. if you’re doing better than i am, you won’t want to relive this shitfest_

Right below that, written in a much newer looking ink, was:

_dear past sans,  
sorry_

The whole page was splattered with what looked to be tearstains, and what Papyrus could only pray was ketchup. Dear god please tell him that’s not blood.

Cautiously, he turned the page. 

It wasn’t as bad. A few stains bled through the pages, but other than that, it was just a normal journal entry.

_picked up this book at the store today. thought it looked pretty cool. dunno what i’m gonna do with it yet, but i guess for now i’ll just act like i’m talking to someone._

_hello book._

_you’re not much for conversation, are you?_

Papyrus stifled a chuckle at that. Of course Sans would try to speak to the book. Why wouldn’t he?

The next few entries were just as normal as the previous one. Sans wrote about what he did that day, things that made him laugh, there was one page that was filled with only knock knock jokes. 

Papyrus had to skip that page.

But above all, the thing Sans wrote most about was Papyrus. About how Papyrus’ school was going, about him meeting Undyne, etc.

After flipping through a few more entries of Sans’ day to day life, one page stuck out to him.

_started my new job at the lab today. i’m the royal scientist’s personal assistant. his name is dr w.d. gaster. he seems like an intimidating guy at first, but after a few of my puns he was throwing them back at me._

_i think me and him are gonna get along just fine._

Ignoring his brother's atrocious grammar, Papyrus felt something prick at the back of his mind. He didn’t remember Sans ever mentioning a Doctor Gaster. And the Royal Scientist? There wasn’t one before Alphys...right?

Confused and intrigued, Papyrus turned to the next page.

_i’ve made quick friends with the whole science team. doctor violet is super nice, she’s like everyone’s big sister._

_doctor rocky is a bit more...rocky. he’s kinda annoying, but fun to be around once you get to know him._

It was strange to see Sans writing so fondly of these people. 

Papyrus felt a little sad thinking about that.

There seemed to be a bit of a time skip between the last entry and the next one.

_been a while since i wrote in this thing. sorry, life happened. i’ll do my best to summarize the past 3 months._

_me and gaster have gotten to be pretty good pals. sometimes i invite him to go to grillbys and he gets super drunk. sadly i’m not old enough to drink just yet, but he’s fun to watch._

So Sans and this Gaster person were close? Again, why had Papyrus never met him?

_some girl named alphys joined the science team. she mostly works with robots and machines, but i’m not complaining. the less i have to be around those things, the better._

Alphys and Sans worked together? What? She never said anything about that. Papyrus didn’t even know the two had ever met! What on earth is going on here?

_despite my protests, we started building a machine. gaster thinks it will let us access another dimension. we’ve titled it ‘project void’ for now. i don’t know how i feel about this._

In the corner of the page, there was a small doodle of what Papyrus supposed the machine looked like. A few strange symbols were written next to it. Odd.

The entries from then on were mostly about the machine. A plethora of math equations, notes, science-y words, and more of those symbols were written all throughout.

There was a short entry highlighted in purple on one page.

_gaster asked me out. i agreed to go on a date with him.  
i may or may not be holding back squeals right now._

Wait.

**W H A T?!**

Gaster and Sans were not only close friends, but lovers? Why hadn’t Sans told Papyrus any of this? And where is Gaster now? Are they still together?

What the hell is going on here?

The entries faded off from scientific notes, to resemble a teenage girls diary about her crush. To be completely honest, Papyrus was surprised. He’d never seen this side of Sans before.

_it’s valentine’s day today and i have no fucking clue what to get for gaster. what does he even like? maybe i should just take him out to a picnic in waterfall? he likes waterfall, and picnics, why not mix the two?_

_update: he loved it and he kissed me ♡_

Oh Sans was totally acting like a young schoolgirl right now. Or, a few years ago, he was. 

Papyrus wasn’t going to lie, it was almost disturbing to be reading this, and not remember any of it. Why did Sans never talk about this Gaster? They were obviously super close, if the entries were anything to go by.

Maybe they had a rough breakup? 

Papyrus was determined to find out, so he continued reading.

_holy fuck holy fuck_

_ok so today was my birthday. and i don’t even know how to write this hold on i need to take a second._

_me and gaster have been together for 2 years now, and so to celebrate, he took me to this beautiful starry cavern in waterfall. (waterfall is our favorite date spot so i wasn’t suspicious of anything)_

_so we get there, and i freak out a little, like oh my god this is so pretty, how did you find this place, the works._

_and this man, this amazing glorious man that i love with all my soul-_

Papyrus knew what those words meant. Every monster did. Gaster had-

_-took out this little box, and opened it. inside, there was a little white soul locket, and before he even said anything, i started crying. he said so many sweet and kind things about me, and how he wanted to spend the rest of his life with me._

_i may or may not have jumped onto him and kissed him._

Oh this was too cute. Sans and Gaster were too cute. Papyrus might’ve died right then and there.

Then it set in.

Slowly, but surely, it set in.

Sans had a soul bond with Gaster.

And Papyrus had never even met this man.

What.

The.

Fuck.

If Papyrus had lacked self control, he would’ve marched to Sans, and demanded answers. But alas, he was a reasonable monster, so he stayed put, and sorted through his racing thoughts.

Soul bonds were not something couples just _did._ When you give someone that white soul locket, you’re bonded to that person for life. 

As in, _till death do us part._

_Literally._

A bad breakup was out of the question.

Something must have happened to Gaster.

That didn’t explain why Papyrus had never even heard of this man's existence! It was almost as though he was reading a fiction book. He felt oddly detached from everything while reading this journal.

Regardless, he needed answers.

And he was going to find them.

_me and gaster told papyrus as soon as he took me home the next morning._

Wait, what?

That never happened.

_to say he was super happy for us would be an understatement. he sprint tackled us and hugged us, before running off to make celebratory spaghetti._

Something was very, very wrong here.

_i don’t think i’ve ever been so happy in my life._

Seeing those words written in Sans’ handwriting should’ve been reassuring, but it only left Papyrus feeling very...unsettled. 

There was something going on here, and Papyrus didn’t like it. 

Not one bit.

This page, out of all the ones he had read so far, had the most tearstains and dried blood. It crinkled the edges of the paper, and Papyrus felt that if he were too rough with the page, it would crumble to dust.

He really shouldn’t be reading this.

He should stop right now.

.  
.  
.

He didn’t.

The next dozen or so entries were happy and cheerful, telling of the process of having Gaster move in with the skeleton brothers.

Something about that made him want to vomit.

According to this book, Papyrus had known this guy so well, that he’d moved in with them. 

_we’ve got most of his stuff moved into my room, but some of his science equipment is down in the basement._

_i dunno how we’re gonna fit him in my room, but we’ll make it work. i’d do anything for him, even if it means getting rid of my sock collection._

Sans was prepared to throw out his entire sock collection? Was he reading the right person's journal?

More importantly, they have a basement?

_we’re still working on ‘project void’ and the machine is almost done. since alphys didn’t want to work on it anymore, gaster had me teleport it downstairs so we could still work on it._

_i try to keep him away from it, i don’t like the feeling it gives me when i’m around it._

_it makes me...uncomfortable._

This machine was definitely important. Why would it be mentioned over and over again if it weren’t? 

Maybe it had something to do with why Gaster wasn’t here right now.

The tone of the journal seemed to change from time to time, but now it was mostly of Sans and Gaster being a happy couple, with the occasional scientific note sprinkled in here and there.

And then, one entry made Papyrus’ soul drop out of his chest.

_gaster’s gone. i don’t know what the fuck happened to him. one minute, we’re getting ready to test the machine, the next, he’s being pulled into it._

_i can still hear his screaming._

_it won’t go away._

_part of me doesn’t want it to go away. it’s the last time i’ll ever hear his voice._

_but that’s not even the worst part, because the universe just loves to fuck me over._

_no one even remembers him. it’s like he got erased from time itself. papyrus asked me who gaster was. everyone i asked had forgotten him._

_i still have a box of his sweaters in my closet. they still smell like him._

_it’s comforting._

A small photo fell from between the pages. It was of Sans, and who he assumed was Gaster. Two words were shakily scrawled in the top left corner.

**“don’t forget”**

**Author's Note:**

> so that headcanons about monster marriage tag? imma explain that real quick if you don't mind.
> 
> i have this headcanon where lockets are a big thing in monster culture (inspired by chara's locket)
> 
> It's a monster tradition. White soul lockets mean romantic love, golden heart lockets mean strong friend/sibling love. Giving someone a white soul locket basically means “I trust you with my soul” Only one is exchanged during a proposal, usually by the one who initiated the relationship. When a white soul locket is given, there is no going back. Monsters bond for life at that point. Only give a white soul locket if you truly want to spend the rest of your life with that person.
> 
> After the soul locket is given, the monsters will go to a place they feel very comfortable and safe in, where they bring out their souls, and perform a Soul Bond. Part of each monsters magic is transferred over to the other, and they can now feel a bit of the others emotions. They are now known as Soulmates.
> 
> In the unfortunate event that something happens to one of the monsters in a Soul Bond, the one that is still alive will feel as though they are being torn in two, because that's kind of what's happening. Their other half is dying/dead, so they only feel an echo of the pain the other is experiencing, but that doesn't make it any better.
> 
> The dead Soulmates dust is usually held in a small container of the living Soulmates choosing, and they loop it onto the locket, so that their partner will always be with them.
> 
> In Sans' case, he isn't left with any dust, and no one even remembers his Soulmate. So he wears one of Gaster's old turtleneck sweaters all the time, and hides his soul locket underneath it.


End file.
